The present invention relates to a particle board and also relates to a method of manufacture of a particle board.
The present invention has applications in the particle board manufacturing industry, but is not limited thereto, the invention also possibly relating to other types of wood-based boards, such as MDF and OSB (oriented strand board). Wood-based boards are in turn used, for example, for the manufacture of furniture and in the building industry.
Known particle boards currently available on the market comprise an upper and a lower layer of finer wood particles and an intermediate layer of coarser wood particles. The particle board is manufactured under pressure and heat using adhesive as binder. The wood particles may be of wood and/or other lignocellulose material and may consist, for example of blade-cut particles from round timber, sawdust or chip particles. Examples of particle material other than wood are flax straw, hemp and bagasse.
Nowadays the intermediate layer is manufactured with an even particle density in order that the particle board will have as uniform a quality as possible over its entire surface. The density of the intermediate layer may be in the order of 660-700 kilograms per cubic meter.
In order produce a known particle board, the finer particle fraction, which has previously been mixed with binder, is first spread out on a belt and is distributed with an even thickness over the belt, the so-called surface particles. The coarse particle fraction, also called the core particles, which have likewise been mixed with binder, is then spread out evenly distributed in a thicker layer over the finer particles. The upper surface layer of a finer particle fraction is spread out over the evenly distributed coarse particle fraction forming a particle mat. The particle mat is then compressed so that most of the air present between the particles is expelled.
The spread particle mat, or the particle mass, is then pressed under pressure and heat. After pressing the board takes on a solid structure and is cooled. Finally, surface planes of the board are sanded in order to eliminate any discolouration and irregularities. The board is delivered and the recipient can apply a suitable surface layer for further processing.
The known method suffers from the disadvantage, however, that the cost of the middle layer of materials, such as particles and binder, is high. Known particle boards are also heavy, which means heavy haulage and unnecessary impact on the external environment.
It is desirable that the particle board should have sound and heat-insulating properties, since it may also be used in the building industry.